对叶榕传粉小蜂性比率的调节和稳定

传粉榕小蜂呈现偏雌的性比率,单双倍体性别决定系统、局域配偶竞争和近交效应被认为是调节偏雌性比率的3个主要机制。通过研究影响对叶榕传粉小蜂性比率的因素,结果表明传粉榕小蜂的偏雌性比率随局域配偶竞争强度的降低而增加;受母代雌蜂交配次数的影响,随着母代雌蜂交配次数的增加,子代的偏雌性比率逐渐降低,这一结果首次揭示了传粉榕小蜂的交配制次数对性比率的影响,并在个体水平上定量了性比率变异与雌蜂交配频次的关系。传粉小蜂的性比率与共生的非传粉小蜂的关系,非传粉小蜂的介入直接减少了传粉小蜂的数量,甚至对传粉小蜂的种群有显著影响,结果发现非传粉小蜂对传粉小蜂雌雄性的分配比率没有显著影响,传粉榕小蜂仍能正常地进行繁殖。传粉与非传粉者小蜂之间作用关系的确定,可为进一步理解两者的稳定共生的机制提供科学证据。     

不同光照质量和刈割强度对小糠草无性繁殖特性的影响

本实验于1996年在美国德克萨斯理工大学草原,野生动物和渔类系的温室和实验室中进行,实验材料均为盆栽糠草,实验设计为在自然光照下（R／FR＝1．1）,以不同留茬高度（10,15,20cm和不刈割）作为不同刈割强度,用不同红光／远红光比例（R／FR＝1．3和0．7）处理不同刈割强度的小糠草,观测不同处理对小糠草无性繁殖特性的影响,结果表明,小糠草净增蘖数随刈割强度增加而减少,除不刈割处理外,光照质量变化（R／FR的比例）对分蘖性能影响不大,所有刈割强度下都不存在分蘖的补偿性生长效应,但幼叶伸长速度随刈割强度的增大而加快,可以认为小糠草应适度利用,强度利用或不利均不利于该草生长发育。     

The effect of light quantity and quality during development on the photosynthetic characteristics of six Australian rainforest tree species

Summary Seedlings of six subtropical rainforest tree species representing early (Omalanthus populifolius, Solanum aviculare), middle (Duboisia myoporoides, Euodia micrococca) and late (Acmena ingens, Argyrodendron actinophyllum) successional stages in forest development were grown in a glasshouse, under four levels of neutral shade (60%, 15%, 5%, 1% of photosynthetically active radiation (PAR) in incident sunlight) and three levels of selectively filtered shade (producing 15%, 5%, 1% of PAR). This design served to analyse the interactions between reduced photon flux density (PFD) and reduced red/far-red (R/FR) ratio in their effects on selected photosynthetic characteristics of each species. The light-saturated rate of photosynthesis was significantly influenced by growth irradiance in five of the six species, with all of these showing a non-linear decrease in maximum assimilation rate from 60% down to 1% PAR. The degree of acclimation to this range was not clearly related to the successional status of the species. Dark respiration was more sensitive to growth irradiance in the early- and mid-stage species than in the late-stage species. Although levels of dark respiration were clearly greater in leaves of early- and mid-stage species from the highest light levels, differences between successional groups were negligible at 1% PAR. Growth in filtered shade, typical of that beneath a closed canopy, resulted in lower photosynthetic capacities and quantum yields in those species which did respond. Although dark respiration rates were more sensitive to filtered shade in the early-stage than in the late-stage species, there was no evidence from other gas exchange characteristics to suggest that overall sensitivity to light quality (as characterised by the R/FR ratio) is greater in early successional-stage species.     

红光与远红光比值对切花菊‘神马’发育和外观品质的影响

为了探讨不同R/FR值对温室切花菊发育进程和品质的影响,以切花菊品种‘神马’(Chrysanthemum morifoliumcv.‘Jingba’)为试材,设计不同红光(R:660nm!10nm)与远红光(FR:730nm!10nm)比值(R/FR)为0.5、2.5、4.5、6.5的LED灯照射处理试验,以自然光为对照(CK),观测不同处理的菊花发育阶段和品质指标。结果表明:与CK相比,R/FR=2.5处理显著加快菊花的发育进程(P<0.05),R/FR=2.5处理下短日照处理到现蕾、现蕾到破蕾及破蕾到收获3个发育阶段分别比CK提前4d、8d和5d,R/FR=0.5处理发育速度最慢,3个阶段分别比CK晚4d、2d和2d;不同R/FR值处理下菊花株高、单株叶龄、单株叶面积、茎粗、花径和花梗长度均随温光效应的增加呈增加的趋势,并在R/FR=2.5时取得最大值;收获时切花菊达到A级和B级产品等级的比例分别以R/FR=2.5和4.5处理最高。本研究发现,R/FR为2.5能够显著促进菊花发育进程和提高菊花的外观品质和A级切花的比例。     

朱红毛斑蛾嗜食性的研究

通过野外调查和室内选择实验,研究了朱红毛斑蛾的食性。自然条件下,朱红毛斑蛾为害榕属植物中的小叶榕和垂叶榕,为害率分别为67.39%和47.61%。在T50时,朱红毛斑蛾对印度榕、对叶榕、无花果、黄葛树、高山榕、小叶榕和垂叶榕的平均取食量分别为0、0、0、0、0、8.62±1.6 cm2和3.79±1.8 cm2;平均取食选择指数分别为0、0、0、0、0、0.69和0.31,说明朱红毛斑蛾仅为害小叶榕和垂叶榕,且对小叶榕有明显偏好性。研究结果证明朱红毛斑蛾为寡食性害虫,提示在园林绿化过程中应尽可能避免选择易受害的单一树种大面积栽种。     

Uncoupling light quality from light irradiance effects in Helianthus annuus shoots: putative roles for plant hormones in leaf and internode growth

An attempt has been made to uncouple the effects of the two primary components of shade light, a reduced red to far-red (R/FR) ratio and low photosynthetically active radiation (PAR), on the elongation of the youngest internode of sunflower (Helianthus annuus) seedlings. Maximal internode growth (length and biomass) was induced by a shade light having a reduced R/FR ratio (0.85) under the low PAR of 157 micromol m(-2) s(-1). Reducing the R/FR ratio under normal PAR (421 micromol m(-2) s(-1)) gave similar growth trends, albeit with a reduced magnitude of the response. Leaf area growth showed a rather different pattern, with maximal growth occurring at the higher (normal) PAR of 421 micromol m(-2) s(-1)), but with variable effects being seen with changes in light quality. Reducing the R/FR ratio (by enrichment with FR) gave significant increases in gibberellin A(1) (GA(1)) and indole-3-acetic acid (IAA) contents in both internodes and leaves. By contrast, a lower PAR irradiance had no significant effect on GA(1) and IAA levels in internodes or leaves, but did increase the levels of other GAs, including two precursors of GA(1). Interestingly, both leaf and internode hormone content (GAs, IAA) are positively and significantly correlated with growth of the internode, as are leaf levels of abscisic acid (ABA). However, changes in these three hormones bear little relationship to leaf growth. By implication, then, the leaf may be the major source of GAs and IAA, at least, for the rapidly elongating internode. Several other hormones were also assessed in leaves for plants grown under varying R/FR ratios and PARs. Leaf ethylene production was not influenced by changes in R/FR ratio, but was significantly reduced under the normal (higher) PAR, the irradiance treatment which increased leaf growth. Levels of the growth-active free base and riboside cytokinins were significantly increased in leaves under a reduced R/FR ratio, but only at the higher (normal) PAR irradiance; other light quality treatments evoked no significant changes. Taken in toto, these results indicate that both components of shade light can influence the levels of a wide range of endogenous hormones in internodes and leaves while evoking increased internode elongation and biomass accumulation. However, it is light quality changes (FR enrichment) which are most closely tied to increased hormone content, and especially with increased GA and IAA levels. Finally, the increases seen in internode and leaf GA content with a reduced R/FR ratio are consistent with FR enrichment inducing an overall increase in sunflower seedling GA biosynthesis.     

西双版纳鸡嗉果榕小蜂繁殖和传粉行为

鸡嗉果榕 Ficus semicordata Buch.-Ham.ex J. E. Sm.是西双版纳地区常见的榕属植物,它是热带雨林生态系统中的一类先锋树种,当热带雨林被破坏后,它最先在林缘、沟谷和路边迅速生长起来,是热带和亚热带地区森林生态系统恢复初期一类重要物种。在西双版纳通过不同样地定树、定期生态学观察和室内剖查不同生长时期的鸡嗉果榕隐头果的方法,对榕小蜂繁殖和传粉行为进行了研究,结果表明,鸡嗉果榕雌雄异株,在西双版纳一年结2～3次隐头果,雌株隐头果内小花由榕小蜂传粉后产生种子。雄株则产生雄花和中性小花,中性小花专门供给传粉小蜂产卵繁殖后代。鸡嗉果榕小蜂Ceratosolen gravelyi Grandi是鸡嗉果榕唯一的传粉昆虫。传粉小蜂的雄蜂比雌蜂早羽化30～90 min,一部分雄虫羽化后,在虫瘿上爬动寻找雌蜂寄生的瘿花,一找到雌蜂寄生的瘿花,就咬破虫瘿的一个小口,把生殖器伸进瘿花与雌蜂交配,一部分雄蜂则在果肉上咬出蜂口。雌蜂交配后,顶大交配孔出蜂爬到雄花区采集花粉,然后,飞出寻找鸡嗉果榕雌花期的嫩隐头果传粉和繁殖后代。到鸡嗉果榕雌株传粉的小蜂能飞翔300～500 m,进果腔传粉行为长达5～27 h,传完粉3～5 h在果腔内死亡。到雄株上繁殖的小蜂一般飞翔在20～100 m左右近距离寻找嫩隐头果,进果腔产卵,每只小蜂在无干扰的情况下可产400多粒卵。除传粉榕小蜂外,在鸡嗉果榕雄株隐头果上还有4种植食、造瘿和复寄生等非传粉小蜂,它们对传粉小蜂的种群繁衍影响很大,常使传粉小蜂的种群数量降低25～70%。每个隐头果内进传粉小蜂量多少对鸡嗉果榕和榕小蜂繁殖有关,最佳进蜂量为3只,高或低于最佳进蜂量对鸡嗉果榕树和它的传粉小蜂繁殖均不利。     

红光与远红光比值对温室切花菊形态指标、叶面积及干物质分配的影响

以切花菊品种‘神马’(Chrysanthemum morifolium Ramat ‘Jinba’)为试材,于2010-2011年设计不同红光(R: (660 ±10) nm)与远红光(FR: (730±10)nm)比值(R/FR分别为0.5、2.5、4.5、6.5)的LED灯照射处理,研究不同R/FR值对温室切花菊形态指标、叶面积形成及干物质分配的影响。结果显示R/FR=2.5处理的植株叶片数、株高、茎粗、花径、叶面积及总干重均为各个处理中最高,R/FR=0.5处理的节间最长。所有R/FR处理的单株地上干物质重量与光质处理天数呈指数-线性模型。随处理天数的增加不同R/FR值处理菊花植株地上部分及地下部分干物质分配指数差异均不显著,叶片和花的干物质分配指数随处理天数的增加分别呈降低和升高的趋势,茎干物质分配指数则呈现先升高后降低的趋势,R/FR=2.5处理下,菊花叶片干物质分配指数和花干物质分配指数最高,而茎干物质分配指数却为最低;R/FR=6.5处理茎干物质分配指数最高,叶片干物质分配指数最低;0.5处理花朵干物质分配指数最低,说明远红光比例增加能够促进干物质向茎中分配,R/FR=2.5处理利于干物质向花朵中分配。     

不同R∶FR值对菊花叶片气孔特征和气孔导度的影响

以切花菊品种\"神马(Jinba)\"为试材,2010年10月至2011年2月间在南京信息工程大学试验温室采用不同Red (660±10) nm: Far-red (730±10) nm值的LED光源短日处理,研究了温室切花菊叶片气孔特征和气孔导度对不同R∶FR值的响应。结果表明:不同R∶FR值短日处理35d菊花叶片的上表皮和下表皮的气孔直径分别以R∶FR值4.5和6.5处理最大,均以R∶FR值2.5处理最小,气孔密度和气孔开度均以R∶FR=2.5处理最高,以R∶FR值6.5处理最低,下表皮的气孔密度、气孔开度明显高于上表皮;不同R∶FR值处理叶片的气孔开张比和气孔指数差异不显著;在相同光强下,菊花叶片气孔导度和光合速率由大到小的R∶FR值顺序依次为2.5、4.5、0.5、6.5。叶片气孔导度与气孔指数、气孔密度、气孔开张比和气孔开度成正相关,与气孔长度和气孔宽度呈负相关;R∶FR值在2.5-6.5范围内,随光质中红光成分增加,叶片气孔密度、气孔指数、气孔开度、气孔开张比和气孔导度显著降低。     

棕果蝠取食对两种榕树种子萌发行为的影响

在实验室利用聚果榕（Fieus racemosa）和对叶榕（Fieus hispida）成熟的果实饲喂笼养棕果蝠（Rousettus leschenaulti）,比较了不同处理的3组种子的萌发行为：（1）棕果蝠粪便中的种子;（2）被吐出的果渣中的种子;（3）成熟果实中的种子（对照）。棕果蝠取食行为显著影响了两种榕树种子的萌发过程,3种不同处理的种子萌发过程及最终萌发率（GP）之间都存在显著的差异。聚果榕种子经过棕果蝠消化道后GP显著降低,而对叶榕种子的GP显著提高。棕果蝠粪便中的聚果榕种子萌发开始（GS）和最短萌发时间（Tmin）均比对照种子延迟了2d,但其粪便中的对叶榕种子G5比对照种子提前了1d,Tmin提前了2d;与之相似,前者种子萌发比果实中种子提前2d达到萌发总量的50％（T50）,但后者没有改变T50。不同种榕果果渣中的种子萌发行为也有重大差异：聚果榕果渣中种子的Tmin和T50均比对照种子延迟1d,GS没发生改变;而对叶榕果渣中种子的Tmin比对照种子提前了3d,GS提前1d,T50没有改变。棕果蝠取食两种榕果后在飞行过程中排泄,进而有效的散布种子;而且通过消化明显改变了种子萌发行为,使种子萌发类型更为多样,增加了种子在不同时空条件下萌发的可能性。     

影响对叶榕及其传粉者繁殖的生态学因素

在西双版纳,分别统计了对叶榕(Ficus hispida)雌花期雌雄果的进蜂量和花后期雌雄果繁殖的多个特征值,以此来探讨自然条件下,影响对叶榕及其传粉榕小蜂(Ceratosolen solmsi marchali)繁殖的因素。结果表明:单果内有效进蜂数量是影响种子生产和传粉榕小蜂繁殖的首要因素,而雌花期进果的传粉榕小蜂并不是都能全部进入果腔传粉或产卵,大部分蜂还未进到果腔就被夹死在顶生苞片层的通道里,能进入雌果内传粉的榕小蜂为(2.72±2.04)只·果^-1,约占总进蜂量的52%;而在雄果里,能进入果腔的蜂量只有(2.08±1.65)只·果^-1,占35%左右。由于雌果内的雌花显著比雄果内的雌花多,结合单果进蜂量雌多雄少的格局,最终单果生产的种子数量 (1 891.63 ± 471.53)比传粉榕小蜂的数量 (367.20 ± 208.02) 多5倍有余。在雌果里,供给传粉的雌花数量与所生产的种子数量之间呈显著的正相关,而没有接受到花粉或不能正常受精的雌花数量与种子数量呈显著的负相关。雄果不仅生产花粉,也是传粉榕小蜂繁殖的场所,在相关于传粉榕小蜂自身繁殖力的因子中,传粉榕小蜂产卵制造的瘿花数量对其种群数量有最大的影响;影响次之的是发育过程中死亡的个体数量,它可降低30%左右的传粉榕小蜂数量;影响排在第三位的是寄主的雌花数量。此外,3类非传粉者的存在,单果内平均可减少30多只传粉小蜂。     

对叶榕传粉榕小蜂在时间格局上的种群动态

在西双版纳热带地区,研究了不同时间里对叶榕传粉榕小蜂的自然种群数量变化规律,并结合控制性放蜂实验获得了实验种群的变化规律。结果表明,在不同年的同月份和同年不同月份,对叶榕传粉榕小蜂自然种群数量变化主要受气候因素的影响,低温的1月和干热的4月对传粉榕小蜂种群繁殖和生长均不利,导致种群数量最低。在人为控制情况下放蜂,不同月放蜂对后代产生雌蜂数量影响非常明显,而对雄蜂数量则无明显差异。在同月相近的不同日放蜂时,对叶榕传粉榕小蜂繁殖的后代种群数量无显著差异。     

Molecular analysis of natural leaf senescence in Arabidopsis thaliana

Using artificial canopies, several authors have shown that horizontally propagated and overall propagated radiation beneath the canopy differ substantially in spectral distribution in the red (R) and far red (FR) wavelengths. Given the lack of information about light quality under real crop canopies, the R:FR ratio of vertical and horizontal radiation beneath field-grown maize, soybean and wheat was monitored until leaf area index (LAI) reached 4, 2.5 and 6.9, respectively.
A Li-Cor 1800 spectroradiometer with a remote cosine receptor fitted with a quartz fibre-optic light-guide was used. To isolate radiation coming from a given direction, a black coated tube was fitted to the cosine receptor. The viewing angle was 15°. In open conditions, the values of R:FR from the upper hemisphere were between 1.07 and 1.20. For vertically and horizontally-propagated light, average values were 1.22 and 0.75 respectively.
Beneath the canopy, both R:FR and photosynthetic photon flux density (PPFD) from the entire upper hemisphere decreased in relation to LAI and crop height. R:FR of the horizontal component were found to be generally much lower than the vertical, which decreased significantly only in the later measurements.
The lowest R:FR values were recorded under wheat and soybean canopies. Even the very low LAIs present at early development stages were enough to cause a sharp decrease of R:FR in the horizontal fluxes. Referring to the entire upper hemisphere, PPFD transmittance and R:FR as a percentage of the external references appeared well correlated.     

对叶榕隐头果内佩妃延腹小蜂属两种非传粉榕小蜂的繁殖特点

2005年8-11月,在西双版纳热带植物园对寄生对叶榕的佩妃延腹小蜂的产卵行为进行了观察,并解剖雄花前期的隐头果观察小蜂利用瘿花资源情况;对不同年份（2003、2004、2005）,不同批次的隐头果内榕小蜂数量进行了统计。结果表明： 对叶榕Ficus hispida隐头果内寄生的佩妃延腹小蜂属Philotrypesis的两种榕小蜂——短尾佩妃延腹小蜂P. pilosa和长尾佩妃延腹小蜂Philotrypesis sp.,都是在果外利用长的产卵器刺穿隐头果果壁将卵产于果中雌花子房内。它们不能为寄主榕树传粉,为非传粉小蜂。短尾佩妃延腹小蜂的产卵时间与传粉榕小蜂接近,几乎与传粉榕小蜂同时到达隐头果产卵,该时期隐头果可供其产卵2天;而长尾佩妃延腹小蜂的产卵时间较晚,在传粉榕小蜂产卵后的第6天开始到果外产卵,并可持续产卵约一周时间。对叶榕雄花期雄果中的瘿花子房由于花梗长度不同而明显分为3层：果壁层（具短花梗）,中间层和果腔层（具长花梗）。短尾佩妃延腹小蜂和长尾佩妃延腹小蜂在紧靠果壁的子房果壁层中分布最多,而很少存在于果腔层的瘿花子房内。在自然情况下,短尾佩妃延腹小蜂和长尾佩妃延腹小蜂寄生榕果的比率因季节和植株个体不同而变化。但无论是对榕果的寄生比率还是单果内寄生的数量,长尾佩妃延腹小蜂一般均比短尾佩妃延腹小蜂高,这可能与长尾佩妃延腹小蜂群体在隐头果上产卵时间比后者更长有关系。